The present invention relates to a disc drive slider, and more particularly to a magnetic recording head slider having a piezoelectric sensor formed therein at the wafer processing level to measure interference levels between the slider and the disc as the slider flies over the disc.
The data density of a high performance magnetic disc drive is highly dependent on the separation distance between the recording head and the recording surface. To meet the ever-increasing need to pack as much data onto the surface of a magnetic disc as possible, the separation distance between the recording head and the disc in commercial high performance disc drives has continued to shrink. Some high performance magnetic recording systems have sliders carrying transducing heads which are separated from the magnetic disc by less than two millionths of an inch. Other systems maintain the recording head in virtual contact with the disc surface, referred to as virtual contact recording (VCR) for proximity recording. The performance tolerances of these systems is currently being controlled by tight supervision of the manufacturing tolerances of the components of the disc drive. However, even with careful control of the manufacturing processes, component or system failures may still occur where the systems degrade over time or where components, such as heads and discs, interfere with each other to cause premature failure.
In the case of flying magnetic recording heads with small glide heights, component or system failures are typically a result of the head crashing onto the surface of the disc. The head crash is often preceded by an increased level of physical interference between the head and the disc. Interference is the turbulence, striking of particulate, or other physical phenomena occurring between the head and the disc surface that affect glide height The interference problem may be caused by environmental factors, component wear, or a combination of both. Environmental conditions such as altitude, temperature, humidity and others affect the flying height of the head. They also affect the tribochemical response of the disc and head surfaces. Component wear due to vibration or contamination can lead to an increased level of particulate at the head/disc interface, which can interfere with the head to disc spacing and ultimately lead to a head crash.
In the case of VCR heads, the heads fly in light interference with the disc surface. Over the course of time as the drive is operated, the interference level may reduce as a result of burnishing of the head and the disc surface, or the interference level may increase due to wear or other factors causing roughness in the interface between the head and the disc surface. Either of these situations affect the performance of the recording head.
One significant problem related to disc drive failures due to interference between the head and the disc is that they are typically difficult to predict. Some disc drives employ systems designed to predict failure, relying on information such as motor torque to anticipate a prospective failure. However, more reliable and direct systems for predicting disc drive failure based on changing interference levels would be an improvement in the art.